1. Field of the Invention
The invention relates to a fault detection apparatus which detects a fault by a current.
2. Description of the Related Art
It is generally known to connect a plurality of batteries in parallel to obtain a large amount of electric power. For example, a large number of photovoltaic (PV) cells are connected in series and in parallel in a large-scale solar power generation system (PV array). In the solar power generation system, a fuse may be used to prevent an overcurrent caused by a short circuit or a ground fault. It is also known to measure a voltage value or a current value to evaluate the output of a solar battery (e.g., refer to Jpn. Pat. Appln. KOKAI Publication No. 2004-77309).
However, when natural energy is used to generate power as in the solar power generation system, a fixed amount of power is not always generated due to conditions of the natural environment such as sunlight. Therefore, an overcurrent may not run even when a fault such as a short circuit or a ground fault occurs. In this case, even if a fault such as a short circuit is detected by the detection of the overcurrent, the fault cannot be detected. Even if a fuse is provided, the fuse may not blow, and operation may be performed in a faulty condition.